This invention relates to the field of tamper-resistant reclosable bags or sacks, and is more particularly concerned with reclosable sacks having a primary non-reclosable fastener and a secondary reclosable fastener.
Various schemes have been proposed for tamper-resistant bags which are equipped with reclosable fasteners and also with some means to preclude access to the contents of the bag without leaving evidence of tampering. Many of these schemes are for packaging relatively small quantities of goods so that plastic tear webs or weakened web areas are adequate to withstand normal wear of handling, packing and shipping.
However, such tamper-resistant closures are not satisfactory for heavier, bulkier goods, such as dog food, charcoal, cat litter and the like, which ordinarily require packaging which will withstand in excess of fifteen pounds contents weight. For this type of goods, the bags have typically only had a primary non-reclosable fastener of some sort. One drawback of this approach to closures for sacks carrying bulky goods is that the sacks are not reclosable, so that the opened packages are susceptible to spillage when upset. In addition, the contents are often liable to attract vermin or to dry out as a result of remaining open. It is desirable that efficient, inexpensive, reclosable means be provided for such sacks for bulky goods because the contents may necessarily have to be poured from the sack by increments with often substantial intervals between demands for more of the sack's contents.
The device of the patent to Ferrell, U.S. Pat. No. 4,241,865, assigned to the assignee of the present application, is an attempt to overcome many of the disadvantages of these prior art non-reclosable packages or sacks. This patent describes a reclosable sack with a primary non-reclosable stitched fastener and a secondary reclosable fastener of a zipper type located outboard of the primary closure fastener. While the invention of the Ferrell patent provides a tamper-resistant reclosable sack for carrying heavy, bulky goods, it also has a drawback in that it is generally complicated to produce. The production of sacks having the primary non-reclosable and secondary zipper fasteners requires several spools of material to be joined in a continuous process. The zipper requires end stops for the travel of the zipper. Further, the zipper requires that the end stops be properly oriented on the bag. In other words, the zipper needs to be properly registered on the bag.